Torque Converter Ballooning.....

Discussion in 'Ranchero Tech Help' started by drlance, Mar 28, 2013.

  1. drlance

    drlance In Fourth Gear

    Messages:
    389
    Location:
    Robinson, IL
    I have a problem with my 79 GT with 302 and FMX.

    If I drive over 60 MPH for more than 20 min., it will leak trans fluid like crazy, drops a quart in 15 minutes..... If I stop it runs out of the trans from the front.
    Once it cools down it seals up and I can add fluid and drive again.
    As long as I stay at 55-60 I can drive all day long and never leak a drop!!!
    I have a new radiator and have tried adding an auxiliary trans cooler, but it just allows me to drive 25 min above 60 before it starts leaking......
    Chatting with my main mechanic ( for things I don't have the equipment to do myself....) He says he believes it is the torque converter 'ballooning', once you get to speed. It seems to have been a problem with FMX, early 727 torqueflights and early powerglides......( not sure the connection...)

    I asked if changing the torque converter would help, I was told no, since the problem is with the transmission itself.....Pumping fluid into the torque converter faster than it can drain.
    I have blown out the cooling lines, not certain what else to do.....???

    Any ideas? Otherwise the car runs and shifts perfect. just takes forever to go places since I am limited to 55 MPH.....( think of all the gas I'm saving.....lol)
     
  2. ribald1

    ribald1 Banned PLATINUM MEMBER

    Messages:
    19,727
    Location:
    California
    Try bypassing the radiator and just run the auxiliary cooler.
    Sounds a lot like a restriction in the return line.
    When you blew out the lines, how did you test for restrictions? Compressed air will put a lot of air out the other end as long as the tube is not completely blocked.
    A true test would be to put a pressure guage on the output of the tranny cooling system, barring that, bypass the cooling system entirely at the transmission as a test.
    A ballooning converter is a much bigger problem than losing tranny fluid. It pushes the crank forward causing rapid wear of the crankshaft thrust bearings.
    All the above is based on the tranny guy having made a correct diagnosis.
    The only place tranny fluid can come out of the front of the tranny is the front seal. An expanding converter would press it into the pump, reducing leakage at the front seal.
    Based on your description, I personally would suspect a leaking pump or a worn input shaft bearing causing a vibration leak at speed. The converter does not discharge fluid into the area behind the front seal normally.
     
  3. drlance

    drlance In Fourth Gear

    Messages:
    389
    Location:
    Robinson, IL
    Just blew compressed air through the lines for about 1 min each.

    I guess I could just replace both lines with new.... That would insure that they were clear.

    wont be this weekend....have company over, so will let you know what I find!

    Thanks ribald!
     

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